The production of certain carboxylic acids

ABSTRACT

Improvements in the production of carboxylic acids of the formula R-COOH wherein R represents alkyl of from four to six carbon atoms via their alkali metal salts are described, which improvements comprise reacting a starting material selected from A. A METHYLKETONE OF THE FORMULA R-COCH3, b. a mixture of said methyl ketone and the corresponding methyl alkyl carbinol of formula C. THE NON-ACIDIC BY-PRODUCT OBTAINED FROM THE OXIDATION OF CASTOR OIL TO PRODUCE SEBACIC ACID, R in (a) and (b) having the aforesaid meaning, with fused alkali metal hydroxide at a temperature between 250* and 375* C.

United States Patent Keenan [45] June 20, 1972 [54] THE PRODUCTION OFCERTAIN Primary Examiner-James A. Patten CARBOXYLIC ACIDS Anamey-Karl F..lorda and Martin J. Spellman [7 21 Inventor: John Francis EdmundKeenan, Cheadle 57 ABSTRACT l-lulme, England u Improvements in theproduction of carboxyllc acids of the for- [7 1 Asslsnw Chi-GettyCorporation. r y. N- mula R-COOl-l wherein R represents alkyl offromfour to six [22] Filed: Apr 24 1969 carbon atoms via their alkali metalsalts are described, which improvements compnse reacting a startingmaterial selected [21] Appl. N0.: 819,084 from a. a methylketone of theformula R--COCl-l b. a mixture of said methyl ketone and thecorresponding [52] US. Cl. ..260/527 R, 260/531 C, 260/540 methyl alkylcarbine] offormula [51] lnt.Cl ..C07c51/00, CO7c5l/3O CH3 [58] Field ofSearch ..260/527 R, 540, 531 C CHOH, and

[56] References Cited W, 1 1 V 7* W c. the non-acidic by-productobtained from the oxidation of UNITED AT PATENTS castor oil to producesebacic acid,

1,926,059 9/1933 Pelton et al. ..260/531 C R in (a) and (b) having theaforesaid meaning, with fused al- 1,926,068 3 slrosficker t a 60/53l Ckali metal hydroxide at a temperature between 250 and 375 2,379,0986/1945 Nixon ..260/540 C. 2,384,8l7 9/1945 Chitwood 260/531 C 2,926,1822/1960 Sutton ..260/531 c 12 Claims W2 2 PRODUCTION OF CERTAINCARBOXYLIC ACIDS The present invention relates to improvements in theproduction of carboxylic acids by the oxidation of ketones, particularlyby the alkali fusion of methyl ketones.

According to the present invention there is provided a process for thepreparation of a carboxylic acid having the formula:

R COOH l by the oxidation of a methyl ketone having the formula:

R COCl-l II with fused alkali metal hydroxide at a temperature between250 and 375 C., wherein R denotes a straightor branchedchain alkylradical containing from four to six carbon atoms per molecule.

The methyl ketone employed in the present invention may be, forinstance, methyl n-butyl ketone, methyl iso-butyl ketone, methyln-pentyl ketone and methyl n-hexyl ketone. The methyl ketone used may bethe pure or substantially pure compound, or, if desired, it may be inthe form of a mixture with other organic substances.

In a particular embodiment of the present invention the carboxylic acidof formula 1 may be prepared by the oxidation of a mixture of a methylketone and the corresponding methyl alkyl carbinol having the formula:

CHOH

wherein R is as hereinbefore defined.

For instance, a mixture of methyl hexyl ketone and methyl hexyl carbinolmay conveniently be.used. Especially useful mixtures are the first groupof non-acidic by-products obtained from the oxidation of castor oil toproduce sebacic acid. The oxidation of castor oil by fusion with alkalimetal hydroxide is a well-known industrial process for the manufactureof sebacic acid from which two distinct groups of nonacidic by-productsdistill off. The first is essentially a mixture of methyl hexyl ketoneand methyl hexyl carbinol; and the second a mixture of alcoholscontaining principally from 14 to 16 carbon atoms per molecule. Thefirst group of non-acidic by-products may, if desired, be used in thecrude form which contains, in addition to the methyl hexyl ketone andmethyl hexyl carbinol, small quantities of higher primary alcohols andolefinic materials. Alternatively, the first group of non-acidicby-products may be redistilled to obtain mixtures comprising essentiallymethyl hexyl ketone and methyl hexyl carbinol, the earlier fractions ofwhich are richer in methyl hexyl ketone than the later fractions.

in accordance with a preferred embodiment of the present invention thereis included in the reaction mixture a surfaceactive agent. Particularlypreferred surface-active agents are the alkali metal salts of suitablephenols or sulphonic acids, especially those which will withstand thehigh temperatures of the reaction and also the action of molten causticalkali. Such surface-active agents may be, for example, the sodium orpotassium salts of capryl phenol, nonyl phenol, Dobanic Acid (.DobanicAcid" is a trade mark and is a proprietary form of an alkyl-benzenesulphonic acid), phenol, hydroxyphenyl stearic acid, resorcinol,B-naphthol, o-cresol, diisopropyl phenol, triisopropyl phenol ormixtures thereof.

The proportion of surface-active agent may conveniently be in the rangeof from 0.1 to 20 percent by weight, and preferably in the range of from1 to percent by weight, based on the weight of the ketone, or where amixture of organic materials is used, on the total weight of organicmaterial for caustic fusion.

The proportion of alkali metal hydroxide used may be, for instance, inthe range of from 1 to 3 molar proportions per molar proportion ofstarting material but proportions in the range of from 1.2 to 1.8 molarproportions per molar proportion of starting material are preferred.

The fused alkali metal hydroxide may be percent potassium hydroxide or amixture of potassium hydroxide and sodium hydroxide. The mixture mayadvantageously contain between 25 and 75 percent by weight of potassiumhydroxide but a mixture containing between 40 and 50 percent by weightof potassium hydroxide is particularly preferred.

The reaction is advantageously carried out at a temperature in the rangeof from 280 to 350 C., and preferably in the range of from 300 to 350 C.The reaction may conveniently be carried out at atmospheric pressure butif desired superatmospheric pressure may be used.

Although the reaction may be carried out in the presence of smallamounts of water, for example up to 5 percent, the use of substantiallyanhydrous conditions in the lower part of the temperature range ispreferred.

In the process of the present invention the alkali metal salt of thecarboxylic acid is produced, and after acidification the free acid maybe obtained by any conventional method, for instance separation of thecrude acid or extraction with a solvent followed by distillation.

The carboxylic acids produced by the process of the present inventionare especially useful as organic intermediates, for example in thepreparation of synthetic lubricants.

The following examples further illustrate the present invention. Partsby weight shown therein bear the same relation to parts by volume as dokilograms to liters. Parts and percentages are expressed by weightunless otherwise stated. The aqueous mixed alkali referred to in theexamples contains 1.04 moles alkali per 100 grams mixture.

EXAMPLE 1 40 parts of potassium hydroxide pellets were placed in a mildsteel vessel fitted with stirrer and thermometer pocket. The outlet ledto an air condenser topped with a Dean and Stark apparatus. Thetemperature was raised to 340 C. and to the stirred alkali was added 50parts of methyl isobutyl ketone regularly over a period of 230 minutes.Heating was completed after a further 30 minutes at the sametemperature, and water was added gradually to dissolve the potassiumsalts and cool the mixture. 4.5 parts of the starting material wererecovered from the Dean and Stark and 11,500 parts by volume of gas wereevolved during the reaction.

The alkaline solution was filtered and the acidified with sulphuricacid. The organic material was extracted with chloroform and washed withwater to remove sulphuric acid, dried and distilled. 34.8 parts ofisopentanoic acid were collected at 67 to 70 C. and 14 millimeters ofmercury pressure. The yield was 77.2 percent.

EXAMPLE 2 82.3 parts of potassium hydroxide and 63.1 parts of sodiumhydroxide were placed in a mild steel vessel similar to that used inExample 1. The temperature was raised to 320 C., and to the stirredalkali was added 260 parts of the first group of by-products in thecrude form, obtained in the manufacture of sebacic acid, dropwise over aperiod of 250 minutes.

36 parts by volume of organic distillate were then returned to thereactor in the same way as the original material over a further periodof 20 minutes.

After a further half-hour at reaction temperature heating wasdiscontinued and 1,000 parts by volume of water were added to thereaction mixture. 15 parts of organic distillate were produced at thispoint, the principal constituents being 2-methyloctenes with smallerquantities of octenes, hexane, methyl hexyl ketone and capryl alcohol,and 86,000 parts by volume of gas were evolved.

After filtering the alkaline solution, it was acidified with sulphuricacid, and the organic layer was washed with water.

The aqueous layer was extracted with chloroform and the extract wasadded to the organic material and distilled.

213.4 parts of 98.4 percent heptanoic acid boiling at 107 to 1 1 1 C. at8 millimeters of mercury pressure were collected. A

EXAMPLE 3 34 parts potassium hydroxide and 7 parts sodium hydroxide wereplaced in the apparatus described in Example 1 and the temperatureraised to 300 C. 65 parts of methyl hexyl ketone of 96.1 percent puritywere then added over a period of 2 to 3 hours while maintaining a steadytemperature. After a further 30 minutes at reaction temperature heatingwas discontinued and 200 parts by volume of water were added to thereaction mixture. 14,000 parts by volume of gas were evolved, and 2.5parts of organic distillate recovered.

After filtering the alkaline solution, it was acidified with sulphuricacid and the resultant mixture extracted with chloroform.

The separate chloroform extract was distilled to remove solvent and theresidue distilled under vacuum. 54.7 parts of 97.4 percent heptanoicacid'boiling at 114 to 116 C. at 15 millimeters of mercury pressure wereobtained. The yield was 83 percent.

EXAMPLE 4 20 parts potassium hydroxide were placed in the apparatusdescribed in Example 1 and the temperature raised to 340 C. 32.5 partsmethyl hexyl ketone of 96.1 purity were then added over a period of 2 to3 hours while maintaining a steady temperature. After a further 85minutes at reaction temperature heating was discontinued and 200 partsby volume of water were added to the reaction mixture. 7,800 parts byvolume of gas had been evolved, and 0.7 part of organic distillate hadbeen recovered.

After filtering the alkaline solution it was acidified with sulphuricacid and the resultant mixture extracted with ethyl acetate.

The separate ethyl acetate extract was distilled to remove solvent andthe residue distilled under vacuum. 30.0 parts of 97 percent heptanoicacid boiling at l 16 C. at 15 millimeters of mercury pressure wereobtained. The yield was 90.9 percent.

EXAMPLE 5 260 parts aqueous mixed alkali (58:42 sodiumhydroxide/potassium hydroxide) and 5 parts capryl phenol were placed ina mild steel vessel similar to that used in Example 1, but with adistillation head fixed immediately to the outlet leading to acondenser.

The temperature was raised to 350 C. by which time 128 parts of waterhad been distilled. To the stirred mixture was added 343.5 parts of thefirst group of by-products obtained in the manufacture of sebacic acidafter being redistilled and containing 30 percent methyl hexyl ketoneand 0.42 percent water over a period of 5% hours, during which time thetemperature was dropped gradually to 312 C. 91,000 parts by volume ofgas were evolved and 57.5 parts of distillate were recovered. Heatingwas discontinued and 1,000 parts by volume of water were added to thereaction mixture.

The aqueous alkaline solution was filtered, then acidified withsulphuric acid and allowed to stand. The heptanoic acid layer wasdistilled under vacuum. 270.4 parts of 98 percent heptanoic acid boilingat 107 to 111 C. at 8 millimeters of mercury pressure were obtained. Afurther 1.9 parts boiling at 190 to 198 C. at 8 millimeters of mercurypressure contained 66.7 percent heptanoic acid.

EXAMPLE 6 434 parts of aqueous mixed alkali (58:42 sodiumhydroxide/potassium hydroxide) and 8 parts capryl phenol were placed inthe apparatus described in Example 5.

The temperature was raised to 330 C. and to the stirred mixture wasadded 500 parts of the first group of by-products obtained in themanufacture of sebacic acid after being redistilled and containing 30percent methyl hexyl ketone and 0.06 percent water over a period of 5%hours.

During the first hour of addition the temperature was allowed to fallsteadily to reach 305 C. and maintained at that temperature during therest of the addition. At the end of the addition period 122 parts byvolume of organic distillate were recovered and returned to the reactionvessel over a period of half an hour bringing the total addition time to370 minutes.

133,000 parts by volume of gas were given off and 51.5 parts ofdistillate were recovered. Heating was discontinued and 1,500 parts byvolume of water were added to the reaction mixture. The products wereworked up as in Example 5 and 422.8 parts of 98.1 percent heptanoic acidboiling at 107 to 1 11 C. at 8 millimeters of mercury pressure wereobtained. A further 12.6 parts boiling at 190 to 198 C. at 8 millimetersof mercury pressure contained 93% heptanoic acid.

EXAMPLE 7 300 parts aqueous mixed alkali 58:42 sodiumhydroxide/potassium hydroxide) and 3.0 parts of Dobanic Acid JN" wereplaced in the apparatus described in Example 5 and the procedurefollowed as in Example 5. 150 parts of water distilled initially.

To the stirred mixture was added 300 parts of the first group ofby-products obtained in the manufacture of sebacic acid after beingredistilled and containing 30 percent methyl hexyl ketone and 3.2percent water over a period of 6 hours.

At the end of the addition period 76 parts by volume of organicdistillate were recovered and returned to the reaction vessel over afurther period of half an hour bringing the total addition time to 330minutes.

94,500 parts by volume of gas were given off and 15.6 parts ofdistillate were recovered. Heating was discontinued and 1,000 parts byvolume of water were added to the reaction mixture, the products beingworked up as in Example 5.

267.4 parts of 98.3 percent heptanoic acid boiling at 107 to l 1 1 C. at8 millimeters of mercury pressure were obtained.

EXAMPLE 8 280 parts aqueous mixed alkali (58:42 sodiumhydroxide/potassium hydroxide) and 5 parts n-nonyl phenol were placed inthe apparatus described in Example 5.

The procedure was followed as described in Example 5, 143 parts of waterbeing distilled initially.

To the stirred mixture was added 300 parts of the first group ofby-products obtained in the manufacture of sebacic acid after beingredistilled and containing 30 percent methyl hexyl ketone and 3.3percent water over a period of 310 minutes.

At the end of the addition period 58 parts by volume of organicdistillate were recovered and returned to the reaction vessel over afurther period of 35 minutes bringing the total addition time to 345minutes.

94,000 parts by volume of gas were given off and 15.0 parts ofdistillate were recovered. Heating was discontinued and 1,000 parts byvolume of water were added to the reaction mixture, the product beingworked up as in Example 5.

263.9 parts of 99.1% heptanoic acid boiling at 107 to 1 1 1 C. at 8millimeters of mercury pressure were obtained. A further 8.3 partsboiling at to C. at 10 millimeters of mercury pressure contained 92.9percent heptanoic acid.

EXAMPLE 9 450 parts aqueous mixed alkali (58:42 sodiumhydroxide/potassium hydroxide) and 8.5 parts capryl phenol were placedin the apparatus described in Example 5. The procedure was followed asdescribed in Example 5, 233 parts of water being distilled initially.

To the stirred mixture was added 522 parts of the first group ofby-products obtained in the manufacture of sebacic acid after beingredistilled and containing 30 percent methyl hexyl ketone and 0.61percent water over a period of 4 hours.

At the end of the addition period 1 parts by volume of organicdistillate were recovered and returned to the reaction vessel over afurther period of 1 hour bringing the total addition time to 5 hours.

160,500 parts of gas were given off and 28.2 parts of distillate wererecovered.

The products were worked up as in Example 5, giving a main fraction of405.5 parts of 98.2 percent heptanoic acid and a second fraction of 32.7parts of 96.3 percent heptanoic acid.

By carrying out the same procedure, but without the addition of caprylphenol, 400 parts of organic distillate were recovered at the end of theaddition period thus demonstrating the advantage of the presence of asurface-active agent in the process.

EXAMPLE 10 432 parts aqueous mixed alkali and 8 parts resorcinol wereplaced in the apparatus described in Example 5. 227 parts of water weredistilled out up to 342 C. under 20 millimeters of mercury pressure.

The temperature was dropped to 330 C. before the dropwise addition of500 parts of the first group of by-products obtained in the manufactureof sebacic acid after being redistilled and comprising 36 percent methylhexyl ketone in octan-2-ol containing 0.06 percent water began. Thetemperature was dropped gradually over the first 100 minutes of theaddition time to 303 C. and retained there until the end of the totalreaction time (390 minutes). The addition was complete after 330 minutesby which time 126 parts by volume of organic distillate had beencollected. The latter was returned to the reactor dropwise during thelast hour of reaction.

153,000 parts by volume of gas were given off and 37 parts of organicdistillate were recovered. Heating was stopped and 1,500 parts of waterwere added giving an additional 4.5 parts of organic steam distillate.

The aqueous alkaline solution was filtered, then acidified withsulphuric acid and allowed to stand. The heptanoic acid layer wasseparated and distilled under vacuum. 448.2 parts of 99.1 percentheptanoic acid distilled at l l8l20 C. at millimeters of mercurypressure. The yield was 89 percent.

EXAMPLE 1 1 430 parts of aqueous mixed alkali and 16 parts of ,8-naphthol were placed in the apparatus described in Example 5. 223 partsof water were distilled out as in Example 10.

500 parts of the first group of by-products obtained in the manufactureof sebacic acid after being redistilled and comprising 36 percent methylhexyl ketone in octan2-ol containing 0.05 percent water were addeddropwise. The temperature dropped from 335 C. at the start to 304 C. in70 minutes and was kept at 303 C. until the end of the total reactiontime (375 minutes) when heating was concluded. This was returned to thereaction mixture during the remaining reaction time.

157,000 parts by volume of gas had been given off and 23.5 parts oforganic distillate had been collected. A further 2.7 parts of organicdistillate were collected during the addition of 1,500 parts of water tothe hot reaction mixture.

The heptanoic acid was recovered as in Example 10 and 445.8 parts (89percent yield) were distilled.

EXAMPLE 12 This was similar to Example 11 .using 431 parts aqueous mixedalkali, 8 parts B-naphthol and 500 parts of the first group ofby-products obtained in the manufacture of sebacic acid after beingredistilled and comprising 36 percent methyl hexyl ketone in octan-Z-ol,and containing 0.05 percent water.

222 parts of water were distilled off initially. The total reaction timewas 370 minutes. The total final organic distillate was 368 parts andthe volume of gas given off was 154,500 parts by volume. 457 parts of 99percent heptanoic acid were distilled off. The yield was 91 percent.

EXAMPLE 13 The reaction and work-up were similar to Example 11 exceptthat 8 parts o-cresol were used instead of the B-naphthol. 432 parts ofaqueous mixed alkali were used from which 220 parts of water wasdistilled before adding 500 parts of the first group of by-productsobtained in the manufacture of sebacic acid which have been redistilledand which comprises 36 percent methyl hexyl ketone in octan-2-olcontaining 0.05 percent water. The initial temperature of reaction was345 C. which was dropped to 302 C. in 60 minutes. The addition time was320 minutes and the total reaction time was 360 minutes.

160,500 parts of gas were given off and the total final organicdistillate was 34.3 parts. 451.8 parts of 99 percent heptanoic acid weredistilled off. The yield was 90 percent.

EXAMPLE 14 The reaction and work-up were similar to Example 11 exceptthat 16 parts capryl phenol were used instead of ,8- naphthol. 432 partsof aqueous mixed alkali were used from which 222 parts of water weredistilled before adding 500 parts of the first group of by-productsobtained in the manufacture of sebacic acid which have been redistilledand which comprise 44 percent methyl hexyl ketone in octan-2-olcontaining 0.06 percent water. The initial temperature of reaction was340 C. which was dropped to 305 C. in minutes. The addition time was 330minutes and the total reaction time was 370 minutes.

The total final organic distillate was 36.3 parts and 145,500 parts byvolume of gas were given off. The main heptanoic acid fraction (99percent heptanoic acid) was 427.8 parts and 36.4 parts of a secondfraction containing 75% heptanoic acid were obtained.

EXAMPLE 15 The reaction and work-up were similar to Example 1 1 exceptthat 8 parts 2,4,6-triisopropyl phenol were used instead of theB-naphthol. 451 parts of aqueous mixed alkali were used from which 235.5parts of water were distilled out before adding 500 parts of the firstgroup of by-products obtained in the manufacture of sebacic acid whichhave been redistilled and which comprise 39 percent methyl hexyl ketonein octan- 2-ol containing 0.02 percent water. The initial temperature ofreaction was 321 C, which was dropped to 305 C. in 50 minutes. Theaddition time was 335 minutes and the total reaction time was 380minutes.

The total organic distillate weighed 43.4 parts and 145,000 parts byvolume of gas were given off. The main heptanoic acid fraction was 433.7parts (98 percent heptanoic acid), and 21.5 parts of a second fractioncontaining 94 percent heptanoic acid were obtained.

EXAMPLE 16 The reaction and work-up were similar to Example 1 1 exceptthat 8 parts of capryl phenol were used instead of )3- naphthol. 452parts of aqueous mixed alkali were used from which 233 parts of waterwere distilled out before adding 540 parts of the first group ofby-products obtained in the manufacture of sebacic acid which have beenredistilled and which comprise 9.4 percent methyl hexyl ketone inoctan-Z-ol containing 0.24 percent water. The initial temperature ofreaction was 330 C. which was dropped to 305 C. in an hour. The additiontime was 360 minutes and the organic distillate (92.3 parts) was notreturned to the reaction. The latter contained 15 percent parts methylhexyl ketone and 52 percent parts octan-2-ol. 163,000 parts by volume ofgas had been evolved.

The main heptanoic acid fraction was 438.6 parts and was essentiallypure, and 3.4 parts of a second fraction were obtained containing 69percent heptanoic acid.

EXAMPLE 17 in octan-2-ol containing 0.05 percent water was begun. The

temperature was lowered gradually over the first 50 minutes of .theaddition time to 303 C. and maintained there for a further 90 minutesbefore lowering it again to reach 293 C. after a total of 180 minutes.The temperature was raised again to 303 C. near the end of the additiontime (335 minutes) and to 308 C. at the completion of the reaction time(380 minutes) by which time no more gas was being evolved. 144,500 partsby volume of gas had been given off, and 34 parts of organic distillatehad collected in the Dean and Stark apparatus. A further 11.3 parts oforganic steam distillate were collected on adding the-1,500 parts ofwater at the end of the reaction time.

The work-up of the product was as in Example 11. 448.4

parts of heptanoic acid were distilled off and consisted of 98 percentheptanoic acid.

EXAMPLE 18 This was similar to Example 1 1 except that 8.1 parts ofcommercial hydroxyphenyl stearic acid were used instead of naphthol. 431parts of aqueous mixed alkali were used from which 224.3 parts of waterwere distilled out before adding 500 parts of the first group ofby-products obtained in the manufacture of sebacic acid which have beenredistilled and which comprise 36 percent methyl hexyl ketone inoctan-2-ol containing 0.06 percent water.

The initial temperature of reaction was 320 C. which was lowered to 300C. in 90'minutes. The addition time was 320 minutes and the totalreaction time was 365 minutes.

The total final organic distillate weighed 44.8 parts and 155,500 partsby volume of gas were given off. The heptanoic acid fraction was 440.6parts and consisted of 99 percent heptanoic acid.

EXAMPLE 19 The reaction and work-up were carried out as in Example 1 1except that the apparatus was made of nickel and 180 parts phenol'wereused instead of the ,B-naphthol.

5,420 parts of aqueous alkali were used from which 2,780 parts of waterwere distilled before the dropwise addition of 6,000 parts of the firstgroup of by-products obtained in the manufacture of sebacic acid whichhave been redistilled and which comprise 36 percent methyl hexyl ketonein octan-2-ol containing 0.06 percent water was begun. The initialtemperature was 328 C. which was lowered to 306 C. gradually during 1hour. The addition time was 410 minutes and the total reaction time was480 minutes.

The organic distillate was 560 parts and 1,476,000 parts by volume ofgas were evolved. The main fraction distilled was 4729 parts (98 percentheptanoic acid) and 240 parts of a higher boiling fraction containing 97percent heptanoic acid were obtained.

EXAMPLE 20 The reaction and work-up was conducted as in Example 19except that the phenolic additive consisted of 300 parts of a mixture of2,6-diisopropyl phenol and 2.4.6-triispropyl phenol.

2,860 parts of water were distilled from the alkali. The weight ofmaterials used and the times and temperatures used were as in Example19.

The organic distillate was 775 parts and 1,452,000 parts by volume ofgas were evolved. The main fraction distilled was 4,810 parts (95percent heptanoic acid) and 54.5 parts of a higher boiling fraction wereobtained containing 88 percent heptanoic acid.

EXAMPLE 21 The reaction and work-up were as in Example 19 except that192 parts of the same additive were used.

5,420 parts of alkali were used from which 2,840 parts of water weredistilled before adding dropwise 6,000 parts of the first group ofby-products obtained in the manufacture of sebacic acid which have beenredistilled and which comprise 36 percent methyl hexyl ketone inoctan-2-ol containing 0.06 percent water. The initial temperature was328 C. which was gradually lowered to 307 C. during the first hour. Theaddition time was 420 minutes and the total reaction time was 480minutes.

504 parts of organic distillate were recovered and 1,458,000 parts byvolume of gas were evolved. The main fraction distilled was 4,992 parts(97 percent heptanoic acid) and 193 parts of a further fraction wereobtained containing 95 percent heptanoic acid.

We claim:

1. A process for producing a carboxylic acid of the formula R-COOl-lwherein R is alkyl of from four to six carbon atoms, said processcomprising reacting a starting material selected from a. a methylketoneof the formula R-COCH b. a mixture of said methyl ketone and thecorresponding methyl alkyl carbinol of the formula CHOH, and

c. the non-acidic by-product obtained from the oxidation of castor oilto produce sebacic acid, R in (a) and (b) having the aforesaid meaning,with fused alkali metal hydroxide at a temperature between 250 and 375C.

2. A process of claim 1, wherein said starting material is selected frommethyl n-butyl ketone, methyl isobutyl ketone and, methyl n-pentylketone, methyl n-hexyl ketone.

3. A process as claimed in claim 1, wherein the proportion of alkalimetal hydroxide used is in the range of from 1 to 3 moles per mole ofthe starting material.

4. A process as claimed in claim 1, wherein the proportion of alkalimetal hydroxide used is in the range of from 1.2 to 1.8 moles per moleof starting material.

5. A process as claimed in claim 1, wherein the fused alkali metalhydroxide is 100 percent potassium hydroxide, or a mixture of potassiumhydroxide and sodium hydroxide containing between about 25 and 75percent by weight of potassium hydroxide.

6. A process as claimed in claim 1, wherein the reaction is carried outat a temperature in the range of from 300 to 350 C and in the presenceof from 0 to 5 percent of water.

7. A process as claimed in claim 1, wherein a surface-active agent isadded to the reaction mixture in a proportion within the range of from0.1 to 20 percent by weight based on the weight of the ketone.

8. A process as claimed in claim 7, wherein the surface-active agent isthe alkali metal salt of a phenol or sulphonic acid which withstands thehigh temperatures of the reaction and also the action of molten causticalkali.

9. A process as claimed in claim 7, wherein the surface-active agent isthe sodium or potassium salt of capryl phenol, nonyl phenol or dodecylbenzene sulfonic acid.

of organic material therein, and the reaction is carried out at atemperature in the range of from 280 to 350 C.

12. A process as claimed in claim 11, wherein said surfaceactive agentis the sodium or potassium salt of phenol, hydroxyphenyl-stearic acid,resorcinol, fl-naphthol, o-cresol, diisopropyl phenol, tri-isopropylphenol or mixtures thereof.

UNITED STATES PATENT GEEPECE QERETEFECATE OF QQRREGMGN Patent 3,671,581Dated June 20, 1972 Inventor(s) John Francis Edmund Keenan It iscertified that error appears in the above-identified patent and thatsaid Letters Patent are hereby corrected as shown below:

Page 1, the line following Application No. 819, 084, insert ForeignApplication Priority Data April 29, 1968 Great Britain 20126 Signed andsealed this 10th day of April 1973 (s EAL) Attest:

EDWARD M.PLETCHER,JR. ROBERT GOTTSCHALK Attesting Officer Commissionerof Patents FORM PO-1050 (1 USCOMM-DC 60376-P69 Us, GOVERNMENT PRINTINGOFFICE: 1959 0-366-334

2. A process of claim 1, wherein said starting material is selected frommethyl n-butyl ketone, methyl isobutyl ketone and, methyl n-pentylketone, methyl n-hexyl ketone.
 3. A process as claimed in claim 1,wherein the proportion of alkali metal hydroxide used is in the range offrom 1 to 3 moles per mole of the starting material.
 4. A process asclaimed in claim 1, wherein the proportion of alkali metal hydroxideused is in the range of from 1.2 to 1.8 moles per mole of startingmaterial.
 5. A process as claimed in claim 1, wherein the fused alkalimetal hydroxide is 100 percent potassium hydroxide, or a mixture ofpotassium hydroxide and sodium hydroxide containing between about 25 and75 percent by weight of potassium hydroxide.
 6. A process as claimed inclaim 1, wherein the reaction is carried out at a temperature in therange of from 300* to 350* C and in the presence of from 0 to 5 percentof water.
 7. A process as claimed in claim 1, wherein a surface-activeagent is added to the reaction mixture in a proportion within the rangeof from 0.1 to 20 percent by weight based on the weight of the ketone.8. A process as claimed in claim 7, wherein the surface-active agent isthe alkali metal salt of a phenol or sulphonic acid which withstands thehigh temperatures of the reaction and also the action of molten causticalkali.
 9. A process as claimed in claim 7, wherein the surface-activeagent is the sodium or potassium salt of capryl phenol, nonyl phenol ordodecyl benzene sulfonic acid.
 10. A process as described in claim 1,wherein said starting material is a mixture of methyl hexyl ketone andmethyl hexyl carbinol; or the first group of non-acidic by-products,either in the crude form or redistilled, which by-products have beenobtained in the manufacture of sebacic acid.
 11. A process as claimed inclaim 10, wherein a surface-active agent is added to the reactionmixture in a proportion of from about 1 to 10 percent by weight based onthe total weight of organic material therein, and the reaction iscarried out at a temperature in the range of from 280* to 350* C.
 12. Aprocess as claimed in claim 11, wherein said surface-active agent is thesodium or potassium salt of phenol, hydroxyphenyl-stearic acid,resorcinol, Beta -naphthol, o-cresol, di-isopropyl phenol, tri-isopropylphenol or mixtures thereof.